Lab 5 / Part 2: Greetings and Madlibs in Python

C O N T E N T S

Recreating Greetings.html but in Python
Recreating Madlibs.html but in Python

Introduction

Once you’ve made these simple programs in JavaScript, doing them in Python will be a piece of cake! The two languages share a lot in common. We’ll do the first of these, “greetings”, together below, and then you’ll have no problem doing the other one, on your own.

We won’t be running Python inside of an HTML script on a website, so in your text editor (e.g. Atom, Sublime Text, etc.) simply create a new file and give it the .py extension. This signals your text editor to invoke the proper syntax highlighting up front. Name this first file greetings.py.

Setup for Python3

Let’s be sure your Terminal session will run Python3 (instead of the prepackaged Python 2.7.x) when calling python on the command line. We can crete an “alias” for python3 by running the following command:

  $ alias python=/usr/local/bin/python3

Alternatively, you can simply run python3 in the Terminal instead of python, but this gets annoying after awhile.

Once you’ve done this, you’re all set. Onto making “greetings.py” …

1. Recreating Greetings.html but in Python

In JavaScript, a variable is declared by typing var like so:

  var myVariable = someValue;

Notice that in addition to our declaration, we also assigned a value (someValue).

In Python, we don’t need to declare a variable… Instead, a variable is automatically “declared” when we assign a value to it. So, we just write:

  myVariable = someValue

(Also, notice that we don’t use the semicolon at the end of a line in Python, as we do in JavaScript.)

To prompt the user for input, we don’t type prompt() as we do in JavaScript. In Python (i.e. Python3) we use the input() method.
So, our first line of code in greetings.py will look something like this:

  username = input("So, like, what's your name? ")

We’ve successfully (1) prompted the user for input, and (2) stored that user input in a new variable called “username”.
The last step is to print it back out in a string back in the console. Our print function in Python is pretty simple:

  print("Look Mom, no semicolon!")

Now, we just have to concatenate a string that includes the input stored in the username variable.
So, this means our 2nd and last line of code in greetings.py will look a little something like this:

  print("Hi, " + username + "!")

Here, we’ve (1) concatenated a string, stored inside our username variable, into a longer string to form a greeting, and (2) we returned this final string to the console with a print() function.

Now we just have to test our python script by running it on the command line.

Back in Terminal, simply type python, then a space, and then drag-and-drop your greetings.py file onto the Terminal window (remember: this will quickly create a full path to your file on the command line!). Run the command by hitting enter, of course.

The output will look like this:

  $ python /Users/louisgoldford/Desktop/greetings.py  
  So, like, what's your name? dumpsterFyreFestival  
  Hi, dumpsterFyreFestival!  
  $

Make sure your file is included in your /lab-05-js-py folder, and don’t forget to add, commit, and push your changes!
Use your git cheatsheet (from lab 3) if you need it!

2. Recreating Madlibs.html but in Python

Now that you’ve seen how easily we can translate our JavaScript code into Python, write new versions of the Madlibs programs you made in Lab 5 / Part 1.

If you’re feeling comfortable, you can skip the 1st version of madlibs (i.e. the one with hardcoded values), and move quickly onto making the final version (i.e. the one with variables prompted with user input using Python’s input() method, described above). You can call it madlibs.py. Don’t forget to test your programs on the command line too.